Is the ozone layer present in both the stratosphere and mesosphere of the Earth's atmosphere?

The correct assessment of the presence of the ozone layer is that it primarily exists in the stratosphere. The stratosphere is the second atmospheric layer above the Earth's surface, and it contains a high concentration of ozone (O3), which plays a critical role in absorbing the majority of the sun's harmful ultraviolet (UV) radiation. This ozone layer is crucial for protecting living organisms on Earth from excessive UV exposure.

While there is some ozone present in the mesosphere, it exists at significantly lower concentrations and does not play the same protective role as it does in the stratosphere. The mesosphere, which is the third layer of the atmosphere above the stratosphere, extends up to about 85 kilometers (53 miles) high. Here, the conditions do not support the same density of ozone as found in the stratosphere.

Therefore, the statement that the ozone layer is present in both the stratosphere and mesosphere is not accurate, making the answer that indicates this is true incorrect. The correct answer is reflected in the understanding that the ozone layer primarily resides within the stratosphere, responsible for its significant protective function.